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A platform for research: civil engineering, architecture and urbanism
Blast-filling of the Vakhsh River cofferdam
Conclusions Damming mountain rivers with a simultaneous building up of the underwater part of the cofferdam by means of directed blasting of heterogeneous rock material piled up on the bank, and dumping it into the body of the cofferdam, is unquestionably efficient.Modeling of this operation is well justified when the line of least resistance, both in the model and in nature, falls within the 1–25 m range; parameters obtained on the model are directly proportional to those required for the principal dam part.In blasting pile-up hard rock material, the factor accounting for the properties of rock mass in Eq. (2), which determined the width of the fill, is reduced by 10–20%.The Belgian Army instruction formula ($ R_{P} $=45·W·n) evidently can be used in determining the hazardous zone of flying fragments.The relative value of the blast effect radius, in the direction of the mountain slope, in blasting the fill grounds, is higher than in the weak rocks: it reaches 1.96.Losses in the blasted rock, incurred in scattering, reached 13%; therefore, to be on the safe side, they should be planned at 15%.The guaranteed volume of the cofferdam, i.e., that below the minimum height of the dumped-in dam, is nearly twice as great in sections with the undermined bank than in the non-undermined. It is therefore recommended always to undermine the bank and to place the rock material at its brink.For the first time in damming practice, previously prepared materials were dumped in the channel, in a predetermined sequence. This also was the first application of long horizontal charges arranged parallel to the line of blast-off. These engineering undertakings turned out to be quite justified and now can be recommended for further use. Application of the long horizontal charge affords a high degree of mechanization of blasting works and of the blasting operation itself; it also ensures a more efficient and uniform throw of the rock mass. In the future, long charges undoubtedly will replace the less effective chamber charges, in large scale blasting.
Blast-filling of the Vakhsh River cofferdam
Conclusions Damming mountain rivers with a simultaneous building up of the underwater part of the cofferdam by means of directed blasting of heterogeneous rock material piled up on the bank, and dumping it into the body of the cofferdam, is unquestionably efficient.Modeling of this operation is well justified when the line of least resistance, both in the model and in nature, falls within the 1–25 m range; parameters obtained on the model are directly proportional to those required for the principal dam part.In blasting pile-up hard rock material, the factor accounting for the properties of rock mass in Eq. (2), which determined the width of the fill, is reduced by 10–20%.The Belgian Army instruction formula ($ R_{P} $=45·W·n) evidently can be used in determining the hazardous zone of flying fragments.The relative value of the blast effect radius, in the direction of the mountain slope, in blasting the fill grounds, is higher than in the weak rocks: it reaches 1.96.Losses in the blasted rock, incurred in scattering, reached 13%; therefore, to be on the safe side, they should be planned at 15%.The guaranteed volume of the cofferdam, i.e., that below the minimum height of the dumped-in dam, is nearly twice as great in sections with the undermined bank than in the non-undermined. It is therefore recommended always to undermine the bank and to place the rock material at its brink.For the first time in damming practice, previously prepared materials were dumped in the channel, in a predetermined sequence. This also was the first application of long horizontal charges arranged parallel to the line of blast-off. These engineering undertakings turned out to be quite justified and now can be recommended for further use. Application of the long horizontal charge affords a high degree of mechanization of blasting works and of the blasting operation itself; it also ensures a more efficient and uniform throw of the rock mass. In the future, long charges undoubtedly will replace the less effective chamber charges, in large scale blasting.
Blast-filling of the Vakhsh River cofferdam
Davydov, S. A. (author) / Strausman, R. Ya. (author) / Shifrin, E. I. (author)
1969
Article (Journal)
English
BKL:
56.30
Wasserbau
Local classification TIB:
770/6550/8000
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